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Verified Answer :

SJ2006

C1/C2 =  2/3

 2pi r1 / 2pi r2 = r1/r2 = 2/3

r1/39 = 2/3

r1 = 39*2/3 = 26

So, your answer is 26cm

Answer:

\(r_{1} = 26\).

Step-by-step explanation:

Given : the ratio of the circumferences of two circles is 2:3. If the large circle has a radius of 39 cm,

To find : what is the radius of the small circle.

Solution : We have given that ratio of the circumferences of two circles is 2:3.

Let \(r_{2}\)  is radius of larger circle and  \(r_{1}\)  is radius of small circle .

Then circumference = \(\frac{2\pi\ r_{1} }{2\pi\ r_{2}}\) = \(\frac{2}{3}\) .

Solving the above equation

\(\frac{r_{1}}{r_{2} }\) =  \(\frac{2}{3}\) .

We have given radius of larger circle = 39 then

\(\frac{r_{1}}{39}\) =  \(\frac{2}{3}\) .

On multiplying both sides by 39.

\(r_{1} = 39 *\frac{2}{3}\).

\(r_{1} = 13 * 2\).

\(r_{1} = 26\).

Therefore, \(r_{1} = 26\).